1. Field of the Invention
This invention, in the field of immunology and medicine, relates to new hybridoma lines and the monoclonal antibodies (mAbs) they secrete which are specific for clinically defined colon carcinoma-associated antigens. The mAbs are useful in vivo for immunodetection and immunotherapy of colon carcinoma as well as for the detection and purification of colon carcinoma-associated antigens.
2. Description of the Background Art
During the process of oncogenesis, a number of cell-surface molecules or markers appear on cells. Such tumor-related markers include oncofetoproteins, neoglycoproteins, sphignolipids, and modifications of existing surface proteins. Such new or altered structures are often shed from the tumor cell surface and appear in the serum or in other biological fluids. The detection of any of these substances or “tumor markers” serves as the basis for diagnosing or monitoring the progress of neoplastic disease.
Early animal studies demonstrated that, among these tumor markers, a subset of tumor membrane protein or glycoprotein antigens were immunogenic. Upon appropriate reintroduction into the tumor-bearing host, typically after surgical removal of the primary tumor, such antigens could effectively block the establishment of new tumor growth.
An attempt to use similarly derived tumor-associated antigens in humans was made by Hollinshead and Stewart using a relatively purified membrane preparation in patients with lung cancer (Stewart, T. H. M. et al., Ann. N.Y. Acad. Sci. 277:436 (1976)). These studies were later expanded to include patients with melanoma and colon carcinoma, wherein different pooled allogeneic tumor preparations were administered in combination with complete Freund's adjuvant (Hollinshead, A. C. et al., Cancer 4:9:1387 (1982); Hollinshead, A. C. et al., Cancer 56:480 (1985)).
The use of Freund's adjuvant was based on observations that normal tissue antigens with this adjuvant produced severe autoimmune responses in animal recipients, whereas in the absence of this adjuvant, no adverse reactions were seen. The adjuvant was thought to promote antigen processing by host macrophages as well as prolong the stimulatory action of the antigen at the site of its deposition (see, for example, Roitt, L. Essential Immunology, 6th Ed., Blackwell Scientific Publications, Oxford (1988)).
The above observations served as the basis for early clinical trials using specific human tumor membrane proteins and glycoproteins as tumor “vaccines.” Various of the tumor-associated antigens which had been isolated and characterized could prolong survival and, in some cases, produce regression of metastatic disease.
With the advent of monoclonal antibody (mAb) technology, it has become possible to obtain pure antibody populations which permit better purification and characterization of the various tumor markers and tumor-associated antigens that are useful for immunodiagnosis or immunotherapy. Many mAbs have been described that have varying degrees of selectivity for tumor antigens (versus normal cell surface markers); some of these tumor antigens are broadly represented across several or many tumor types, whereas others appear to be truly tumor-specific. A number of these mAb-tumor antigen systems are described below.
Herlyn et al., Proc. Natl. Acad. Sci. USA 76:1438 (1979), discloses two mAbs obtained by immunizing mice with human colorectal carcinoma (CRC) cells. The mAbs have selective reactivity with human CRC cells. One mAb, 1083-17 (the forerunner of 17-1A), is now known to react with a 41 kDa glycoprotein (see below).
Herlyn et al., J. Clin. Immunol. 2:135 (1982), described the detection of a circulating colorectal carcinoma (CRC)-associated antigen by a mAb developed against a membrane antigen of the SW116 cell line. MAbs 19-9 and 52a, which recognize a monosialoganglioside antigen (Magnani, J. L. et al., Science 212:55 (1981)), reacted with cells of 8 of 12 CRC lines as well as with the cells of one gastric carcinoma and one pancreatic carcinoma. MAb C414 reacted with four of six CRC cultures and with gastric tumor cells. The binding of mAbs 19-9 and 52a to tumor cells were inhibited by a CRC patient's serum. However, CRC sera inhibited binding less frequently than did sera from patients with pancreatic or gastric tumors.
Girardet et al., J. Immunol. 136:1497-1503 (1986), disclosed mAbs against human colon carcinomas. The L-D1 mAb reacted with a 41 kDa glycoprotein, believed to be the same antigen as that defined by mAb 1083-17-1A (Herlyn et al., 1979, supra). The L-C5 mAb precipitated proteins having molecular weights of 43, 45, 47 and 53 kDa from LoVo colon carcinoma cells. L-D1 did react with cervical carcinoma lines, while L-C5 reacted with breast carcinoma lines. Their binding to pancreatic carcinomas was not examined.
Greiner et al., Science 235:895-898 (1987), discloses mAb 06.2 which reacts with a 90 kDa glycoprotein allegedly found in 75-80% of breast carcinomas and more than 90% of colon carcinomas.
Sakamoto et al., U.S. Pat. No. 4,579,827 (Apr. 1, 1986), discloses a number of mAbs said to be useful for diagnosing or treating human colon cancer by a number of different approaches. None of these mAbs is shown to react with a human colon carcinoma-associated antigen that is a protein of either  61 or 72 kDa molecular weight, distinguishing these antibodies from the antibodies  33.28 antibody of the present invention (described below). Furthermore, none of the Sakamoto mAbs have the degree of colon tumor specificity of the mAbs disclosed in the present application.
Delaloye et. al., J. Clin. Invest. 77:301 (1986), discloses the use of a mAb specific for carcinoembryonic antigen (CEA) to detect colorectal carcinoma in vivo using 123I-labelled fragments and emission computerized tomography. The mAb described bears no relation to the mAbs of the present invention.
Douillard et al., Hybridoma 5, Suppl. 1:S139 (1986), describes mAb 17-1A and its cytotoxic properties to gastrointestinal adenocarcinomas in vitro. 17-1A was used with some degree of success in immunotherapy trials. This mAb is said to recognize a 38-41 kDa protein and has a broad range of reactivity and lack of colon tumor specificity, clearly distinguishing it from the antibodies of the present invention.
Scannon et al., U.S. Pat. No. 4,590,071 (May 20, 1986), discloses mAbs specific for melanoma antigens conjugated to toxic proteins such as ricin A chain and the use of these compositions to treat melanoma. There is no disclosure directed to colon tumor antigens or antibodies and their uses.
The relatively pure antigen preparation containing the immunogenic colon carcinoma membrane antigens to which the mAbs of the present invention are directed was originally described by Hollinshead et al., Science 177:887-889 (1972).
The clinical evaluation of the above antigen preparation, including a description of its immunogenicity and potential for enhancing patient survival through stimulation of specific active immunity, was described by Hollinshead et al., 1985, supra.
The work of the present inventors leading to the present invention is briefly described in an abstract by Tsang et al., “Monoclonal Antibodies to Human Colon Carcinoma Associated Antigens,” Intl. Symp. Biotech. in Clin. Med., Rome, Italy, Apr. 13-15, 1987. This reference was made available to the public less than one year before the filing of the ultimate parent application (U.S. Ser. No. 07/176,337) for the present application.